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Eco Village, Sofia Bulgaria

Program: Residential
Location: Mramor, Area Vrubnitsa - Sofia

Client: Sofia Manucipality
Area: 21 240 sq. m.
Year: 2014
Data: Competition project

Team: arch. Guergana Barabonkova LEED AP
            arch. Sayo Okada LEED AP
            eng. Rumen Yordanov LEED AP
            arch. Dragos Fodoreanu
            cand. arch. Katerina Dimitrova
            cand. arch. Konstantin Vazharov
            Sachi Sato
            eng. Rumyana Kulina

Walkable, Ecological, & Self-Sustained Community. The main objective of the proposal for the Eco Village is to develop an example of sustainable construction, to motivate, educate, and inspire Bulgarian and European public for the implementation of sustainable methods and technologies in construction.

The site is located near Mramor village, a suburban area located 12 km from Sofia. The master plan is designed to minimize automobile access within the village while allowing a public transportation/car access route at the perimeter. There are three types of paths: pedestrian, bike and wooden. Pedestrian paths are for everyday use for people traveling on foot or on bike, while allowing enough width for public cars or emergency vehicles to access. Bike paths are dirt roads for people to enjoy on a daily basis or for a weekend bike ride within the village. The wooden paths connect the four-season theme park that runs from the north to the south within the site. The four-season theme park includes spring, summer, autumn, and winter, where each park will have trees bloom during those seasons. For example, the spring park will have flowers such as tulips, snowdrops, and hyacinth planted, which will bring small animals such as birds and bees that favor those flowers. The winter park will have a lake, which will be used for ice skating during the winter. The people from the village will gather together at the ice skating ring and celebrate the winter holidays.

Public buildings, retail stores, and entertainment spaces are in the center of the site. This encourages people to stay in the village without having to go to remote places by car. Community gardens are for people living in the village to utilize for its fresh produce, and the soil is to be fertilized from the compost station located throughout the village. Car use is limited for residents within the village. For those who own vehicles, there are parking spaces (including barrier free spaces) available at the perimeter of the site, covered with photovoltaic panel roofs. The eastern corner of the site has a district heating facility. The facility is to provide district heat to the community by a ground heat source pump as well as bio diesel oil from recycled cooking oil collected by people in the village.

The site is located in a suburban area where the local topography is flat and without natural protection against wind, which provides conditions for a high number of air changes per hour when natural ventilation is used. In this aspect, the natural settings are favorable for ventilating the site. The site master plan is designed in order to minimize
the wind shadow within the site as well as beyond the site boundary.

Design: The design provides three types of housing: apartment, cluster and single-family. The concept is that peoples’ living styles change based on the stages of their life. By providing these three types of housing, people can stay within the village without relocating to a different area to search for suitable living conditions. The site design loosely designates areas for each type of unit, which houses people of similar age and family status.

Energy Performance:
All three units are modeled with PHPP (Passive House Planning Package), and all three types of housing meet Passive House requirements. Singlefamily house energy use is analyzed per Bulgaria's Regulation RD-16-1058 for the energy consumption characteristics of the buildings. Our calculation has proven that single-family, cluster home and apartment building design is 50% less than referenced building energy use, which results in Class A building.

Materials that are specified in this project are carefully selected to have the following characteristics: renewable, recycled, possibility of original system incorporation, or regional. We have calculated the eco-factor for each material. The sum of the eco-factor is multiplied by the cost of the material and then divided by the total cost, which results in less than 30%. The construction materials specified are cautiously chosen not to contain Formaldehyde, VOCs, Radon, Pesticide, or Fibres. All buildings are to have a 24-hour balanced ventilation system and the building envelopes are designed to not have a thermal bridge, which will prevent mold growth. The analysis of thermal comfort of the single-family house shows that the walls’ maximum Delta T is 0.68 °C, and the windows’maximum delta T is 2.90 °C. This fulfills the competition program requirements and also proves that there will be no mold growth on the building envelopes. As for summer comfort, the calculation of buildings in PHPP shows overheating during summer months to be less than 6.2%, which meets Passive House certification requirements. This analysis allows us to believe that the proposed buildings are to have excellent indoor thermal comfort and air quality. The site master plan is designed to include renewable systems. Cooking oils from households are recycled and used as bio diesel at the district heat facility.

We also calculated the building primary energy use and the amount of photovoltaic panel generated electricity, and it shows that the photovoltaic panel will cover more than 80% of the building’s energy use (this calculation excludes public buildings on the site). Lastly, construction cost analysis of this proposal shows that we will be able to achieve
496 € / m²) which is less than the average construction cost for Sofia (831€ / m²). The proposed cost does not include the PV system.

The proposal of an eco-village near Mramor, Bulgaria creates a low-carbon, selfsustained community with easy modular construction. Our hope is this proposal to become a very good prototype and an example for creating other ecological communities in Bulgaria.